This study examined the birth distribution for adolescent (i.e. <20 years) and mature age players (i.e. ≥20 years) selected in the Australian Football League (AFL) National Draft between 2001 and 2012. Birth-date information was accessed for all first time AFL national draftees and players were then classified as either adolescent (N = 736) or mature age (N = 70) draftees. Chi-squared analysis showed a clear bias in the birth distribution of adolescent draftees towards players born in the first part of the classification period for both quartile (P < 0.001) and half-year (P < 0.001) compared to the Australian national population. There was a reverse relative age effect (RAE) for mature age draftees, with a significant bias towards players born in the latter part of the selection period for both quartile (P = 0.047) and half-year (P = 0.028) compared to the Australian national population. The selection bias towards relatively older players in adolescent AFL draftees may be related to advanced physical and psychological maturity, and exposure to higher-level coaching compared to their younger counterparts. The reverse RAE in mature age draftees is a novel finding and supports the need for strategies to encourage continued participation pathways for talented Australian football players born later in the selection year.